MIME-Version: 1.0
References: <CAFiTN-u5D5o_AGNbHRZHaOqAMWkxLf+hSk_r9X3gv6HbLOB5+g@mail.gmail.com>
 <CALj2ACViThGQDYi-yeqUeHqG2Pozn2AiyvtDtjE6zhhbM0KsEA@mail.gmail.com>
 <CAA4eK1+44b3vd_OWfiaVNtjf5Njb5cek09pmKRmttBByeg0NoA@mail.gmail.com>
 <CAFiTN-v3L0WacCDx5dkOSonaZQbJfstXL4HrCPD1ahRdUsRnSg@mail.gmail.com>
 <CALj2ACW63uuxh0fSoxEAF8OMWhz1dJKSkp268WJDzf5BUqCf5g@mail.gmail.com>
 <CAFiTN-s9WWLOhW1TO27NtJwGf0bh2+MWyp3NEkZFeN_S5_p_rA@mail.gmail.com>
 <CAA4eK1LxnsEx5sMbQkK5MHAgXKPROMQXQ0n=fKMwz+UsfKQaMQ@mail.gmail.com>
 <CAD21AoDj+c4LXf2y4ESR-gVyv9d8V0G4R8R9pn-PcmT5zPzYcg@mail.gmail.com>
 <CAA4eK1KokmAwNOL6bS-ip_E3F96PiQTjC4j-M+5vD1T6uUyi3Q@mail.gmail.com>
 <CAFiTN-vFKE8E_N6h+peX9DP92mxCeFdm5A9Esn4DkLmNcZ-dOA@mail.gmail.com>
 <CAFiTN-shLYf-fOTQ_dBf3Xfx05gxs_8d93MHZXyyz6w2Bg5geQ@mail.gmail.com>
 <CAFiTN-tEgkKQHUikn6iBFCYf7XOObR7ncUq=OVh7WEk=6P4ymw@mail.gmail.com>
 <CAFiTN-tQiakd8m+-d6WN6RpJXSv_JcropZ2oGzme4d1JudQhYg@mail.gmail.com>
 <CAJpy0uDKbYWt+YPADj=4fHEvrGEWgnG1n_YsiGT_EZiZf0VSAw@mail.gmail.com>
 <CAFiTN-t82BiXen+HfdR9jZyOpuSO92xonnUK=khXsiZWBfOxMA@mail.gmail.com>
 <CAJpy0uAu2paxGAEffD=vaBTW9Jqbtxxawb8K8FgiASfeKPnGog@mail.gmail.com>
 <CAJpy0uC0ZWgHOivJ102A1fMkppwK3RuSMafRPKyjwkmJrjhVUw@mail.gmail.com>
 <CAFiTN-vFV9-zajrwjYHYyFnyQsooOAXW4CpxB5f-iT3APjOtoQ@mail.gmail.com>
 <CAJpy0uBeU1dZgaqsSVKc=P=EVUKxRgVuHR8jDXFL-HLibbE-kQ@mail.gmail.com>
 <CAA4eK1+FOkOxhzVLAnDymoNjp4i98H-L1+ZsWDgJEv-ndnTzTA@mail.gmail.com>
 <CAFiTN-sVK6Bp+BawCJU_WpAXQSTX4OkKmce5EE4YNBgD-XSjZw@mail.gmail.com>
 <CAA4eK1LbjV0bctib9wUnBpEkC+2rZFPnGuRtrKuc5AtUAzum+A@mail.gmail.com>
 <CAFiTN-vq50N3QP9p3_SH+tJ8Pn=uRDb0X4qEcQZYcGW9AX88rQ@mail.gmail.com>
 <CAFiTN-u3+zRGPESP5kUUfa6NxaWh1HL-gd1225KJ0Uvzi1urow@mail.gmail.com>
 <CAA4eK1L4iNk6mNTC83PbYrRfUdtivH4U961PkdFfOO7mvc=USg@mail.gmail.com>
 <CAFiTN-v+Mh64UfR5zb5rwgyGm6HS80XRSZ_XeaWkg8=+s9o3Kg@mail.gmail.com>
 <CAFiTN-s3ZFHteQsiC3H4=AjTWxuwN-w69XQ3xL5X6YOMTua4pA@mail.gmail.com>
 <CAJpy0uDe724nY59j-8hMapZ_Fru1Wo-NucF4Ea1B3Jrw=+J+UQ@mail.gmail.com>
 <CAFiTN-uR=86L_5tyiA7n73EXCSCuDfQKfL5O=c8n7zZom8_ONQ@mail.gmail.com>
 <CAD21AoDfOS-J0M9WbM3D20eGbSPzbfLQ-9XoYkxO4AZ9twqyvg@mail.gmail.com>
 <CAFiTN-vMTg2X7vwfHLr5Gvy8ViV63_iaEcpHmM8V5GpA9-u8cg@mail.gmail.com>
 <CAA4eK1+b2Ws0e_ZYJsgZAPn7VWndxAK_YM_QMKcfXst3e7F6Jg@mail.gmail.com>
 <CAFiTN-v6hFKMPrSyTBsz=AtEETYMbOxrqvhZJsPQqKgQc4WCLw@mail.gmail.com>
 <CAA4eK1KV3rYkaxys5fh-PtE9kq5xrFbiaRpOSPoRgQG494ek+g@mail.gmail.com>
 <CAFiTN-utvu=QjY1QQ1a_TvkpkpvesMWo9M8wTFYLaOTPdpOJvw@mail.gmail.com>
 <CAA4eK1+HoSOEqNwT3twArPNx4_D7hSUoEg2LnYhX8n9iUwhXgQ@mail.gmail.com>
 <CAFiTN-tqmsfW0Sk=1RhzuduxqLrf9KEc8VOvBae+4aYxWTJwuA@mail.gmail.com>
 <CAA4eK1JmCQ=DHe3HsqpX+P3mGDUd_Z7E7oAxdstK6822W6tuCw@mail.gmail.com>
 <CAFiTN-uE4eAUYewuq3c5deAt3TtVork+H6rkUHRv68cOGr5rmQ@mail.gmail.com>
 <CAFiTN-sJbhPX+LbA8YuQeYJpfGA2XA+OKXf8jCm04RoJOyzLvw@mail.gmail.com>
 <CAJpy0uBPOyWj9itFjHzGXfrUuYS8KGmAvgdcV_9FPjWZ0EZz_w@mail.gmail.com>
 <CAFiTN-s=iLE4qM4qmw9yXKqW09R_c_HqaSGeZXJ2EaTVfXss+g@mail.gmail.com>
 <CAA4eK1KYo0vZpPSRc_4gVpa06-J39gxjs3tHFyckgkBfYJSfFA@mail.gmail.com>
 <CAFiTN-vrKc6OWzrg6yvpwYcj79k=zkrDp3uwiZzjwrWLJAq6tw@mail.gmail.com>
 <CAA4eK1LmvrfEgn1NUZZ=E3yMCjQdNZ5=_SBEry73-EmF6jM_PQ@mail.gmail.com>
 <CAFiTN-vjfub5b3PqPQzfOw9BSjm8jt28ott+Hoz9CrRxJHzYkg@mail.gmail.com>
 <CAFiTN-v=ANapYvRK+SOy2wJb4CSuD6Vb6_bTGuReM9Dv+3tucA@mail.gmail.com>
 <CALDaNm1zEYoSdf2Ns-=UJRw95E5sbfpB0oaNUWtRJN27Q1Knhw@mail.gmail.com>
 <CALDaNm3USsXVNBsfdpkp60HVgrTV4taWMk1xZYNBa7QUF=V0jg@mail.gmail.com>
 <CAFiTN-sNg9ghLNkB2Kn0SwBGOub9acc99XZZU_d5NAcyW-yrEg@mail.gmail.com>
 <CAJpy0uAF3EYcYdpTHdKMeXfvaPbNvnWrZUATrSLL1hqjao=33A@mail.gmail.com>
 <CAFiTN-uikggCKp2LscTorKY5d3KF9j93DW0xebDcRX86G+ZsSw@mail.gmail.com>
 <CAJpy0uDaOoVK8S3_xxTAcTDpfK1AY7tApw7nPOZG_gUz+DMi=Q@mail.gmail.com>
 <CAA4eK1+AdeC5B9xrAXSKWGtTh-0d8xdD=fZttmOBm+c8o8thAQ@mail.gmail.com>
 <CAFiTN-skBQAeuzuUd+PDK0Gqc8g+4x9ypBMwJhOrmW8ZCFKGSA@mail.gmail.com>
 <CAJpy0uCdrsW5T+okq7xTOVxagje7FW3DOeY5B0CGKYa5VqF_tQ@mail.gmail.com>
 <CAFiTN-u+_mFj9caYYFO7=_YHFXk5y=vvOm2H2=5hctYktmAVGA@mail.gmail.com>
 <CALDaNm1aivk9KgQ5daeF6YZzuE+0wWc2yb7wb6qikNyvfPN0Sg@mail.gmail.com>
 <CAJpy0uD6fTEUYJx3+yDbvB=VW7c5AaGoeSd7iwHdYYO=kYGn3g@mail.gmail.com>
 <CALDaNm2YOOdJ25X1sJ+DYz37K6Qi4g0ZNFHb_pQMF9UqancnEA@mail.gmail.com>
 <CAHut+PtMS5bENS0DVtBj+s3kUEOq61+hSkqLODjFB78egB0imQ@mail.gmail.com>
 <CAFiTN-s_M83sfs+MHHbUrMesjsCPN4JWxY5MChCEiY1U-u7=9g@mail.gmail.com>
 <CAFiTN-vj8NTm9w_L2XdhxJCub_RZw__YVUgfXa1B1kJzJctRNw@mail.gmail.com> <CAJpy0uBDLnfhuSiev8W9ZMFNTzUmqhds2dKayUpLoN-z1dtsLA@mail.gmail.com>
In-Reply-To: <CAJpy0uBDLnfhuSiev8W9ZMFNTzUmqhds2dKayUpLoN-z1dtsLA@mail.gmail.com>
From: Dilip Kumar <dilipbalaut@gmail.com>
Date: Tue, 13 Jan 2026 16:09:30 +0530
Message-ID: <CAFiTN-uL9f0X+=Ep4BbAPvaTJA7S4XHM--G4BsnPJw4uJW7EGQ@mail.gmail.com>
Subject: Re: Proposal: Conflict log history table for Logical Replication
To: shveta malik <shveta.malik@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, vignesh C <vignesh21@gmail.com>, 
	Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, 
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://www.postgresql.org/message-id/CAFiTN-uL9f0X%2B%3DEp4BbAPvaTJA7S4XHM--G4BsnPJw4uJW7EGQ%40mail.gmail.com>
Precedence: bulk

On Tue, Jan 13, 2026 at 3:59=E2=80=AFPM shveta malik <shveta.malik@gmail.co=
m> wrote:
>
> On Sat, Jan 10, 2026 at 6:45=E2=80=AFPM Dilip Kumar <dilipbalaut@gmail.co=
m> wrote:
> >
> >>
> > Here is the updated patch
> >
>
> Thanks, I will review the code. Few concerns while experimenting with 001=
 alone:
>
> 1)
> I am able to insert and update rows in pg_conflict.pg_conflict_16394.
> It should be restricted.
>
> 2)
> I think we need to block 'SELECT for UPDATE' and similar operations on
> CLT. Currently it is allowed on CLT.
> See this:
>
> postgres=3D# SELECT * FROM  pg_toast.pg_toast_3466 for UPDATE;
> ERROR:  cannot lock rows in TOAST relation "pg_toast_3466"
> postgres=3D# SELECT * FROM pg_conflict.pg_conflict_16394 for UPDATE;
> ....

I sent an analysis on this a few days ago but realized it only went to
Amit. Resending to the full list:

So the summary is, currently, all INSERT/UPDATE/DELETE operations are
blocked for TOAST tables for safety. However, I have allowed these
operations for the pg-conflict table. Unlike TOAST, the system does
not internally reference conflict data, so user manipulation doesn't
pose a safety risk to the system. If a user modifies or deletes this
data, they simply lose their logs without impacting system stability.
What are your thoughts on this approach?


>> I  Wrote
> I have been exploring the enforcement of these restrictions.
> Currently, DML is validated via CheckValidResultRel(). If we do not
> explicitly check for the conflict log table in that function, DML
> operations, including DELETE, will be permitted. While I am not overly
> concerned about users attempting manual INSERT or UPDATE operations.

> Now for TRUNCATE, the truncate_check_rel() currently relies on
> IsSystemClass() to restrict truncations. Since the conflict namespace
> is included in IsSystemClass() to prevent unauthorized DDL, TRUNCATE
> is blocked by default. We could allow it by adding an exception in
> truncate_check_rel() (e.g., IsSystemClass() &&
> !IsConflictNamespace()), but I am unsure if this is necessary. Do we
> really need to permit TRUNCATE, or is allowing DELETE sufficient for
> user-driven cleanup?

>
>
> 3)
> We currently skip ANALYZE on TOAST tables, but I=E2=80=99m not sure wheth=
er
> the same restriction should apply to CLT. Since users are expected to
> query CLT frequently, collecting statistics could be beneficial. Even
> though there are currently no indexes or other structures to enable
> more optimal plans, having statistics should not harm. Thoughts?
>
> postgres=3D# analyze pg_toast.pg_toast_16399;
> WARNING:  skipping "pg_toast_16399" --- cannot analyze non-tables or
> special system tables
>
> postgres=3D# analyze pg_conflict.pg_conflict_16394;
> ANALYZE

I think its good to ANALYZE CLT data because user logically never need
to query the toast data, but they would have to query the conflict
data.

> 4)
> It will be good to show 'Conflict Log Table:' in \dRs command.

Yeah, you raised this point earlier as well, somehow I am missing this
point from the last few versions. I will analyze this and change this
as a first comment in the next version.

--=20
Regards,
Dilip Kumar
Google